Electromagnetic sound-reproducing apparatus



Nov. 6, 1928.

.E. F. HOLINGER ELECTROMAGNETIC SOUND REPRODUCING APPARATUS Filed April 25, 1927 ATTORNEY Patented Nov. 6, 1928.

UNITED STATES PATENT OFFICE.

EMIL I. HOLINGER, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALE TO E. CHASE CROWLEY, OF NEW YORK, N. Y.

ELECTROMAGNETIC SOUND-REPRODUCING APPARATUS.

Application filed April 23, 1927. Serial No. 185,994

This invention is applicable to the reproduction of sound waves generally, but'is more articularly designed for use in radio-receivmg sets and comprises certain improvements on the construction disclosed in my pending application, Serial No. 133,581, filed Se t. 4 1926. In this invention, as in that disclosed in my said prior application, the resonant' member consists of a hollow, substantiall globular body of resonant material to whic the armature of the electromagnetic receiving element is attached, but I have found that the quality and volume of the tone re roduction is considerably increased if sai globular member has a circumferential crease formed in its walls and one or more openings through said walls located in said crease.

The best form of apparatus embodying my invention at present known to me is illustrated in the accompanying sheet of drawings in which,

Fig. 1 is a side elevation and a partial vertical section of the apparatus with parts broken Fig. 2 is another vertical section on a smaller scale taken on the line 22 of Fig. 1. Fig. 3 is a side elevation on a smaller scale of the completed apparatus partly broken away, the view being taken at apoint at right angles from that on which Fig. 1 is taken.

Fig. 4 is a erspective detail showing the armature and the portion of the attached resonant member broken away, and I Fig. 5 is a detail cross section taken on line 5-5 of Fig. 3.

Throughout the drawings like reference characters indicate like parts. 1 is the base of the unit, 2 a ermanent magnet mounted therein, and hel by set screws 3, 3. Soft iron pole-pieces 4, 4', are fastened to the poles of magnet 2 and provided with the magnet coils 5, 5. A cover 6 for the electromagnets is held to the base of the unit by set screws 6, 6*.

The armature 9 for the magnet is preferablymade by stamping out a thin, softiron plate havinglthe central opening 11', the exte rior upwar y bent flange 12, and the laterally projecting ears 13 13 arranged opposite best sliown in Fig. 4. This one another as armature is fastened to the lower portion of the resonant member 16 by shellacking or otherwise attaching the walls of said member to the flange 12.

This armature is pre erably supportedby springs 7,7, of non-magnet -terial such as brass, which may be clamped into the base 1 and against the permanent magnet 2 by set screws 8, 8, as shown in Fig. 1. The upper ends of these springs may be fastened to the armature 9 by the screws 10, 10 as shown, or by welding or soldering or other convenient means. a

14 is a vertical rod set in the base 1 projecting upwardly through opening 11 in the armature 9 and through the interior of the resonant member 16 to the upper portion thereof, said resonant member being fastened to the upper end of said rod by any convenientclamping means 15 as indicated in Fig. 3.

The resonant member 16 is made of any tough, resonant material such as cardboard and may be conveniently made in a plurality of sections such as 16, 16, 16, and shellacked or otherwise rigidly fastened together at their edges as indicated in Fig. 3. This member is preferably substantially globular in shape, although other forms creating a substantially enclosed air chamber may be employed. This globular member 16 is provided with one or more creases 17 in its walls, and extending around it. Preferably one such crease is pro- .vided along a great circle of the globe, the

plane of said great circle being parallel to the plane of the armature 9, and consequently at right angles to vertical support 14. One or more holes 18, 18 are formed in the walls of the member 16 and preferably located in said crease 1-7.

Washers or wedgin members 19, 19, are located in the curves 0 spring .7, 7, so as to be capable of being drawn more or less into said curves by any adjustable fastening means such as bolts and nuts 20. Obviously when these nuts are tightened up, more or less, the springs 7, 7, will be correspondingly flexed outward and upward, thereby slightly raising the armature 9, the lower ends of the spring 7, 7, being firmly anchored in the base 1.

In assemblin and operating my invention I proceed as fo lows: The armature 9 is slid in to the opening in the base of the resonant member 16 and cemented therein, the member 16 and armature are placed over the support 14,'and the former clamped thereon by set screw 15 with the lower ends of the springs 7, 7, inserted in the base 1, and the set screws 8, 8, are then set up firmly against said springs, with the armature 9 resting on the ends of the pole-pieces l, 4. The screw bolts 20, 20 are then tightened so as to raise the armature 9 the desired distance away from the ends of the pole-pieces 4, 4, the coils 5, 5, are connected up with the receiving set, and the apparatus is ready for sound reproduction.

I find that the tone of the reproduction varies with the diameter and thickness of the armature 9, being lower in pitch and fuller in volume as the weight of the armature is increased.

The advantage resulting from the use of the crease 17 is the bringing out, ,or the full development, of the over-tones and this result is further heightened by the cutting of the holes 18 in the wall of the member 16, especially if they are located as shown in said crease 17. Preferably the crease 17 should have a cross section of flowing curves as best shown in Fig. 5.

The volume of reproduced sounds can be varied b adjusting the distance of armature 9 from t e pole-pieces 4, 4, of the magnet by meansof tightening up the bolts and nuts 20, 20 as above described. In Fig. 1 the parts are shown in broken lines in the initial position with the armature resting on the polepieces, and in full lines in one operative position.

Obviously various changes could be made in the relative arrangement and special construction of the constituent elements herein described and illustrated without departing from the. principle of operation disclosed, or

entirely losing the beneficient results secured by my invention.

Having described my invention, I claim:

1. In a sound reproducing device suitable for use in radio apparatus having an electromagnet, the coils of which are adapted to be included in the reproducing circuit, the combination, with the above recited apparatus of a hollow, substantially globular member made of thin, resonant material having an o ening in its side, and an armature for said ectromagnet fastened to said globular mem- 2. A structure such as defined in claim 1 combined with a support for said globular member attached to it at a point substantially diametrically opposite to that at which said armature is attached.

3. A combination such as defined in claim 1 in which said globular member has a circumferential crease in which said opening is located. I

4. In a sound reproducing device suitable for use .in a radio receivin set having an electromagnet, the coils of'w 'ich are adapted to be included in the reproducing circuit, the combination, with the above defined apparatus, of a hollow, substantially globular member made of resonant material having a cir cumferential crease provided with a series of openings therethrough, a support for said member at a point remote from said crease, and an armature for said electromagnet attached to said member within the field of said magnet at a point on the side of said crease opposite to that on which the first mentioned point of support is located.

5. In a sound reproducing device suitable for use in a radio receivin set having an electromagnet, the coils of which are adapted to be included in the reproducing circuit, the combination, with the above defined apparatus, of a hollow, substantially globular member made of resonant material having a circumferential'crease, a support for said member at a point remote from said crease, and an armature for said electromagnet attached to said member within the field of said magnet at a point on the side of said crease opposite to that on which the first mentioned point of support is located.

6. In a sound reproducing device suitable for use in a radio receiving set having an electromagnet, the coils of which are adapted to be included in the reproducin circuit, the combination, with the above defi ned apparatus of a vertical support extending upward from said magnet, a hollow, substantially globular member of resonant material surrounding said support, fastened thereto at its upper portion and having a circumferential crease of curved cross section in its medial portion and an armature for said ma et located in the field thereof and fastene to the lower portion of said globular element.

7. A combination such as defined in claim 6 in which said globular member is provided with a series of openings through its walls located in said crease.

8. In a sound reproducing device suitable for use in radio receiving set having an elec tromagnet, the coils of which are adapted to be included in the reproducing circuit, the combination, with the above defined apparatus, of an elastic, resonant member, a rigid support for said member,- an armature clamped directly to said member at a point remote from said support and located in the field of said magnet, and springs forming the sole additional support for said armature, said spring being rigidly mounted with reference to said magnet at one end, and clamped directly to said armature at the other.

9. A structure such as defined in claim 8 combined with means for slightly flexing said springs to adjust the distance of said.armature from said magnet,

10. A sound reproducing device suitable for use in a radio receiving set, comprising the combination of an electromagnet, a resonant member, an armature attached to said resonant member, a curved spring rigidly mounted with reference to said magnet at one end and fastened to said armature at its other end, a wedge member located in the curved portion of said spring, and means carried by said spring for forcing said wedge member into said curved portion, whereby the position of said armature with'reference to said magnet may be adjusted.

11, A sound reproducing device suitable for use in a radio receiving set, comprising, in combination, a horse-shoe magnet, a hollow, substantially globular resonant member made of stiff fibrous material having an opening in its lower wall, a support for said member extending upward through said opening to the upper portion of said member,

an annular armature for said magnet surrounding said support and fastened to the wall of said resonant member around said opening, two curved springs rigidly mounted with reference to said magnet and supporting said armature at diametrically opposite points thereof, wedge-shaped ,members located in the curved portions of said springs, and adjustable clamping means attaching by said sprlngs may be flexed to secure any desired adjustment of said armature with reference to said magnet.

12. A combination such as defined in claim 11, in which said globular member has a crease in its walls along a great circle, the plane of which circle is parallel to that of said armature.

13. A combination such as defined in claim 11, in which said globular member has a crease in its walls along a great circle, the plane of which circle is parallel to that of said armature, and a series ofperforations in its walls located in said crease.

14. A combination such as defined in claim 11 in which said globularmember has a crease in its walls of wave like cross section, said crease extending along the/circumference of a circle, the plane of which circle is parallel to that of said armature.

EMIL F. HOLINGER.

said wedge members to said springs, wheree 

